Control system



March 20, 1934- e. B. SCHEIBELL 1,951,446

CONTROL SYSTEM Filed June 5, 1929 2 Sheets-Sheet 1 4 INVENTOR.

Gorglgn Brown J'c/Letbell ATTORNEY March 20, 1934- G. B. SCHEIBELL 1,951,446

CONTROL SYSTEM Filed June 5, 1929 2 Sheets-Sheet 2 a; 2 4a 3? z: 25 J8 4 S,

INVENTOR aara'o z b Brawn ficketbell ATI'ORN EY Patented Mar. 20, 1934 NITED STATES PATENT QFFICE CONTROL SYSTEM Application June 5, 1929, Serial No. 368,693

8 Claims. (Cl. 175-375) This invention relates broadly to control systems. More specifically this invention relates to control systems in which energy of a. small magnitude is employed to control the circuits through which considerable power is distributed.

An object of this invention is to provide a control system in which a relatively small quantity of energy is employed to control the distribution of relatively large quantities of energy.

Still another object of this invention is to pro vide an arrangement in which energy of a small magnitude mechanically controls the distribution of energy of relatively large magnitude.

A further object of this invention is to provide an arrangement in which small changes in energy control circuits in which energy of relatively large magnitude is distributed.

Still a further object of this invention is to provide an arrangement in which small changes in energy are caused to mechanically control circuits in which energy of relatively large magnitude is distributed.

Another and further object of this invention is to provide a quickly acting arrangement in which small changes in heat energy are caused to control the circuits in which relatively large electric currents are distributed.

Still another and further object of this invention is to providean arrangement in which a thermally operated element is employed to release circuit establishing members that are associated with relays.

Other objects and features of this invention will be apparent to those skilled in theart to which this invention pertains from the following specification and appended claims.

According to this invention a thermally operated element, preferably in the form of a bimetallic coil, is mounted adiacent to a plurality of movable trip rods which are provided with projecting members adapted to be engaged by a movable portion of the thermally operated element when the element is subjected to a change in temperature. Relays are located with respect to the thermally operated element in such a manner that the movable pawls engage members associated with the movable circuit establishing elements of the relays and release selected ones of these latter elements when the thermally operated elementis subjected to a change in temperature. r

interconnecting circuits are provided between the windings of the relays and contacts of the movable circuit establishing elements so that the whole system operates automatically once it is properly installed. The system of this invention has numerous advantages in that small changes in temperature occurring in the medium surrounding the thermally operated element are caused to control the operation of circuits in 160 which currents of relatively large magnitude, such as are employed to energize heating units, are distributed.

In the drawings, Fig. 1 illustrates an embodiment of this invention; Fig. 2 illustrates a modiflcation 01 this invention; Figs. 3, 4, 5, and 6 illustrate modified forms of the trip rods embodied in this invention; and Figs. 7 and 8 illustrate modified forms of the thermally operated mechanism embodied in this invention. .7

Reference numeral 1 of Fig. 1 of the drawings, designates a spirally shaped bi-metallic coil unit, one end of which is held in position by the member 2. A pair 01 trip rods 3 and 4 are slidably positioned in the members 3a and 4a adjacent to .76 the free end 5 of the termally operated unit 1. Pins 6 and 7 are mounted upon the trip rods 3 and 4, respectively, for engagement with the free end 5 of the thermostat unit. Pawl members 14 and 15 are mounted upon the armatures 10 and 11 LED 01 the relays 8 and 9, respectively. Springs 14a and 15a are provided to the pawls 14 and 15 for normally holding the pawls in extended position.

Coil springs 12 and 13 are mounted upon the armatures 10 and 11 respectively, between the members 15 and 18 and the housings for the windings of the relays 8 and 9, for rapidly actuating the armatures 10 and 11 upon the release or the pawls 14 and 15. Contact supporting members 16 and 17 of insulating material, such as phenol condensation products, are mounted upon the armatures 10 and 11. Contacts 16b and 160 are supported upon the member 16. Contacts 16a and 16d are positioned adjacent to "the member 16 in such a position that contacts 16a and 16b are adapted to engage each other and contacts 16c and 16d are also adapted to engage. Contacts 171) and 170 are supported by the member 17 in such a position that contact 17b is adapted to engage contact 17a, which is adjacent to the member 17, and contact 170 is adapted to engage the contact 17d which is also adjacent to the mem-. ber. Other contacts 18a and 19a are supported by the members 18 and 19, which are of insulating material, upon the armatures 11 and 10, respectively. Adjacent to the members 18 and 19 are positioned contacts 18b and 1922 which cooperate with contacts 18a and 19a and establish connection therewith upon the release or the armatures 11 and 10, respectively. Contacts 18b and 1917 are E the engagement of the trip rods 3 and 4 with the mounted .upon resilient supports and follow contacts 18a and 19a, respectively, when the armatures 11 and are being reset by the action of the solenoids of relays 9 and 8, respectively. Upon pawls 14 and 15 the circuits between the contacts 18a and 18b and the contacts 19a and 19b are interrupted.

Connections are provided between the heater unit and the contacts 160 and 17a. Connections are also provided between the source 21 of current supply for the heater unit 20, and the contacts 16d and 17b. The contacts 16a and 18b and. the contacts 170 and 191) are connected together as illustrated in Fig; 1 of the drawings. A

terminal of the current supply source 22 is connected to a terminal of each of the windings of the relays 8 and 9. Connections between the windings of relays 8 and 9 and the contacts 19a and 180, respectively, are also provided- In operation when the temperature of the medium is decreasing the temperature of the medium surrounding the thermally operated unit 1 causes the free end 5 of this unit to move in the direction of pin '1, which is mounted upon the trip rod 4.

The trip rod 4 is caused to move out of engagement with the pawl 15 and release the armature of relay 9. The circuit between the contacts 170 and 17b is completed and the circuit between the contacts 18a and 18b is also completed. The source of current supply 21 is connected to the heating unit 20 and the temperature of medium surrounding the thermally operated unit 1 is caused to rise. The free end of the unit 1 moves toward the pin 6 and the trip rod 3 is caused to move out of engagement with the pawl 14, where upon the armature oi the relay 8 is released for upward movement. The circuits between contacts 16a and 16b and the contacts 19a and 192) are completed. The circuit of the heating unit 20 is interrupted at the contacts 160 and 16d. Simultan'eously with the closing of the circultbetween contacts 16a and 16b the relay 9 is energized by current fromthe source 22, the armature 11 is pulled back toward the relay 9; the trip rod 4 caused to engage the pawl 15 and the circuits between the contacts 18a and 18b and the contacts 174: and 1712 are interrupted. The circuit between the contacts l'lc and 17:! is established and since the contacts 19a and 19b are in engagement the energizing circuit of the relay 8 is completed through the source 22 whereupon the relay 8 draws the armature 10 toward it against the tension of. the spring 12 so that the trip rod 3 engages the pawl 14 and the circuit of the winding of the relay 8 is broken between the contacts 19a and 191). As the temperature of the medium surrounding the thermally operated unit 1 decreases, the cycle of operation of the system is repeated.

In Fig. 2 a modified form of this invention in which a pair of corrugated thermally expansible members 1a and 1b are employed to'actuate the trip rod pin engaging member in in accordance with temperature variations in place of the spirally shaped iii-metallic member 1 illustrated in Fig. l, is shown. The thermally operated elements 1a and 1b are joined together and supported by the bolt and nut 10 upon a bracket id. A rod 1e which protrudes through an aperture in the member 1h is,fastened upon the element 1a. A pair of semi-spherical nuts 1} are positioned upon the rod 1e adjacent to the member 1h. for transmitting motion from the rod 1e to the member in. The end 5b of the member 1h is pivotaliy mounted upon a panel. The end 5a is adjacent to the trip rods 3 and 4 for transmitting motion to the trip rods.

Where it is desired to adjust the temperature 'at which the unit 1 operates the trip rods 3 and 4 the position of the pins engaged by the free end of the unit 1 may be made movable as illustrated in Figs. 3, 4, 5 and 6 of the drawings.

In Figs. 3 and 4 the trip rod 23 which is similar to the rods 3 and 4 of Fig. 1 is provided with a slot 24 in which the body portion 26 of the pin is positioned. A flange 28 and a thumb nut 27 are provided to the pin for hearing against the sides of the trip rod 23 adj acent' to the slot. The thumb nut 27 is employed to adjust the tension of the pin and to prevent the pin from shifting in position once itis set. Another modification of the trip rod is shown in fragmentary cross-section in Figs. 5 and 6. The form illustrated in.

Figs. 5 and 6 is more readily adapted for use in cases where precision adjustments of the pin 30 are required. The rod 31, which is provided with a small knurled knob 32 ispositioned in a hollow portion of the trip rod 29 for operatively en-.

aging the threaded pin actuating member 33 which engages the element 34 upon which the pin wall 33a of the unit 43 is firmly fastened to stationary members 35. The trip rod 44 is fastened to the wall 331) of the unit 43. When the unit 43 is subjected to a change in temperature the wall 33b will move either toward the wall 33a or away from it depending upon whether the change in temperature is negative or positive, that is, falling or rising temperature. The trip rod 44, which is firmly fixed to the wall 33b through the action of the nuts 34a and 34b, which cooperate with a threaded portion of rod 44, is moved longitudinally and disengages either one of the pawls 34c 01'. 34d, which function to release armatures of relays in the same manner as pawls 14 and 15 (Fig. 1) function to release armatures of the relays 8 and 9. Both ends of the trip rod 44 move simultaneously, however, only one of the pawls 34c and 34d is released at onetime since the trip rod moves toward one of the pawls into further engagement therewith, while it moves away from and out of engagement with the other pawl. In practice it may often be desirable to adjust the position of the extremities of the rod 44 with re- In case the unit 43 is filled with a liquid, a

piece of corrugated tubing 36a, the respective ends of which are either soldered or otherwise attached to the rod 44 and the wall 33a is provided to prevent the fluid from escaping from the unit 43.

In Fig. 8 of the drawings a bi-metallic unit 36, which may be either of a circular or of a ribbon shape, is provided for actuating the trip 37 in accordance with temperature changes. The nuts 38 are positioned upon the rod 37 on each side of the unit 36 for transmitting the movement of the unit to the rod. The unit is supported by the members 39 and 40. Temperature changes of the medium surrounding the unit 36 cause the unit to be deformed and to move the rod 37 longitudinally in a manner similar to that in which the rod 44 (Fig. 7) is moved.

The arrangement of this invention may be employed for controlling the temperature of different rooms or compartments where substantially con-- stant temperature is desired. It is especially adapted to directly control the current consumed by heating units without the use of additional relays. In case it is desired to directly control the operation of a plurality of series connected heating units which are positioned about a compartment and which are energized by a current transmitted at a relatively high voltage the members l6 and 17 together with the contacts associated therewith may be positioned in oil filled compartments so that the relatively high voltage circuit is interrupted in oil. Where circuits carrying relatively large currents are interrupted it may also be desirable to provide oil filled compartments about the members 16 and 17 in order to prevent sustained arcs from burning the contacts associated with these members.

It is of course, understood that while I have described several embodiments of my invention that other modifications thereof may be made without departing from the scope and spirit of my invention, that therefore I do not desire to limit this invention to the exact details as described in the foregoing specification except in so far as they are defined by the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In control systems of the class described the combination of an electrically isolated device adapted for developing mechanical motion from heat energy, a relay system comprising a plurality of relays, armatures for said relays, circuits interconnecting the winding of one of said relays and contacts associated with the armature of another one of said relays whereby the energization of said first mentioned one of said relays is controlled by said second mentioned one of said relays, and means mechanically operable by said device for directly mechanically initiating the operation of the armatures of said relays in accordance with changes in temperature.

2. In control systems of the class described the combination of an electrically isolated device adapted for developing mechanical motion from ,heat energy, a relay system comprising a plurality of relays, each of said relays having an armature, circuits interconnecting contacts of said armatures and the windings of said relays, and means mechanically operable by said device for directly mechanically initiating the operation of the armatures of said relays in accordance with temperature changes, said means being adapted to control the operation of the armature of a selected relay during temperature and another armature during decreasing temperature.

3. In a control system the combination of a thermally operated unit, switch elements, means adapted to retain said switch elements in a predetermined position, said thermally operated unit mechanically operating said means to release said switch elements in accordance with temperature changes, and electromagnetically operated means for automatically resetting a released one of said switch elements.

4. A control system comprising a thermal device for exerting amechanical force in different directions depending upon ambient temperature conditions, a plurality of mechanical trigger devices for independently exerting mechanical forces in addition to the mechanical forces exerted by said thermal device, one of said trigger devices'being positioned to be tripped by the force exerted by said thermal device in one direction and another of said trigger devices being positioned to be tripped by the force exerted by said thermal device in another direction.

5. A control system in accordance with claim 4 including electromagnets for resetting said trigger devices and circuit elements mounted on said trigger devices and connected with said electromagnets and energizing means in a manner such that the energizing circuit to one of said electromagnets for setting a previously tripped trigger device is completed by the tripping of another of said trigger devices.

6. A control system comprising, a plurality of spring driven members having contacts thereon, a plurality of movable members each of which mechanically engages with one of said spring driven members for normally retaining the respective spring driven members in predetermined positions, a thermal device for producing a mechanical force in different directions depending upon ambient temperature conditions, said spring driven members each exerting a mechanical force developed independently of the mechanical force produced by said thermal device, one of said movable members being actuated by said mechanical force in one direction for releasing one of said spring driven members and another of said movable members being actuated by said mechanical force in another direction for releasing another of said spring driven members.

7. A control system having the features of claim 6 including electromagnets for resetting said spring driven members to be retained by the respective movable members, and connections among said contacts, said electromagnets and energization means whereby the releasing of one of said spring driven members completes an energizing circuit to an electromagnet associated with a previously released spring member for resetting the same.

8. A control system comprising, a bi-metallic device for producing mechanical movement due to unequal flexure of the bi-metallic parts thereof, a plurality of mechanical trigger devices having parts mechanically accessible to said bimetallic device whereby the movement of said device causes the selective tripping of said triggers, a plurality of electromagnets and a circuit whereby said electromagnets are controlled by the tripping of said triggers for setting said triggers in a position to be again tripped by said bi-metallic device.

GORDON BROWN SCHEIBELL. 

